[2] When Madrid FC endorsed a tournament in the capital in the May festivities which become known as Copa de la Coronación, the forerunner of the Copa del Rey founded a year later, Vallarino organized a series of matches at Tiro del Pichón as part of New's build-up to the tournament, and these games were played by the members of the club divided into two teams: one dressed in white, led by Ángel Mayora, and another in red, led by Vallarino, who shone the brightest, netting several goals, including a hat-trick on 19 March to help his side to a 3–0 win and a brace on 23 March in a 3–2 win.
[4] New was thus one of the five teams who participated in the Copa de la Coronación, and since the figure of coach as we know it today did not exist at the time, it was Vallarino, the president and captain of the club, who was in charge of making up the line-ups and dictating the tactics to be followed.
[2] He did not lose his goal-scoring instinct at Madrid, and quickly became the club's starting striker, and in his first season at the club, Vallarino played a pivotal role in helping the Madrid team reach the first-ever Copa del Rey final in 1903, featuring in the final alongside the likes of Federico Revuelto, the Giralts (Mario, José and Armando) and Antonio Neyra.
[10] It was common at the time for players to leave their respective teams to join or found others due to the still dispersed and confusing growth of football.
[10] Vallarino played a crucial role in helping Español de Madrid win the 1903–04 Centro Championship,[11] hence qualifying for the 1904 Copa del Rey, which ended in controversy as they were unable to participate in the final, meaning Athletic were declared winners again.